Studies On Antibacterial Character And Mechanism Of Water-Insoluble Polymeric Antimicrobial Material With Grafting-Type

Two kinds of water–Insoluble polymeric Antimicrobial Material with Grafting-Type were synthesized, And the antimicrobial property and antibacterial mechanism of them was mainly researched using Escherichia Coli as a disease-leading bacterium and with the method of plate counting live bacterium.The Polystyrene which was grafted on silica gel was chloromethylated using 1,4-bis(chloromethoxy) butane(BCMB) as the new type chloromethylation reagent, and then the chloromethylation particles (CMPSt/SiO₂) was obtained. Then CMPSt/SiO₂ was quaternized using triethylamine(TEA),tributylamine(TBA) and triphenyl- phosphine(TPP) as the quaternary reagent. Finally Water-insoluble polymeric antimicrobial materials QN-PSt/SiO₂ and QP-PSt/SiO₂ which carried the quaternary ammonium salt and the quaternary phosphonium salt were prepared. The chemical structures of the products were characterized with FTIR spectra and chemical analysis. The effects of various factors on the quaternary reaction were mainly researched. The experiment results show that various reaction conditions, such as the reaction temperature, the property of solvent and the structure of quaternary reagent, will influence the quaternary reaction. The quaternary degree of the product is higher as the fine solvent of CMPSt is used and tertiary amine agent with smaller steric hindrance is used.In this paper, the antibacterial property of QN-PSt/SiO₂ and QP-PSt/SiO₂ were mainly investigated using Escherichia coli (E. coli) as a disease-leading bacterium. Influences of various factors on the antibacterial property of QN-PSt/SiO₂and QP-PSt/SiO₂, such as quaternary ammonium (phosphine) degree, and pH value, were examined with the method of the plate counting live bacterium, and the antibacterial mechanism of QN-PSt/SiO₂ and QP-PSt/SiO₂ was studied seriously using the method of measuring the quantity of extracellular DNA and RNA and the activity of TTC-dehydrogenase. The experiment results show that QN-PSt/SiO₂ and QP-PSt/SiO₂ possesses very strong antimicrobial ability, The antimicrobial ratio reaches 100% when contacting with bacterium suspension of 10⁹CFU/mL under the conditions of contacting time of 1⁴min and a dose of 15g/L for QN-PSt/SiO₂ and QP-PSt/SiO₂,The antibacterial activity of QP-PSt/SiO₂, which is attributed to quaternary phosphine salt-type materials, is much stronger than QN-PSt/SiO₂ with quaternary smmonium salt-type. For QN-PSt/SiO₂, the product prepared form tributylamine has stronger antibacterial ability than that prepared from triethylamine. The quaternary ammonium (phosphine) degree influences QN-PSt/SiO₂ and QP-PSt/SiO₂ antimicrobial property to a greet extent, and the higher the quaternary ammonium (phosphine) degree is, the better the antimicrobial activity is; In a certain region of pH value, the higher the pH is, the stronger the antimicrobial ability is. The results of TTC-dehydrogenase activity measurement and extracellular DNA and RNA quantity measurement show that the antimicrobial mechanism of QN-PSt/SiO₂ and QP-PSt/SiO₂ is based on a sterilizing bacterium process.N-vinyl pyrrolidone was grafted on silica gel particles, resulting in the grafting particles PVP/SiO₂. The complex reaction between PVP/SiO₂ and iodine was conduced in ethanol as the solvent. The Immobilization of povidone–iodine was realized, and the functional particles PVP-I₂/SiO₂ was obtained. The effects of various factors on the complex reaction were examined. The structure and composition of the functional particles PVP-I₂/SiO₂ were characterized with infrared spectrum determination and chemical analysis method.The sterilization property of the particles PVP-I₂/SiO₂ was studied with Escherichia coil as a disease-leading bacterium and using the method of plate counting live bacterium. The experimental results show that the suitable temperature for the complex reaction is 60℃, and the complex degree is increased with the increase of the iodine concentration. At 60℃a maximum complex degree of 0.16% (wt%) could obtained as iodine was dissolved in ethanol in saturated state. The particles PVP-I₂/SiO₂ have very strong sterilization activity. The sterilization rate can reach 100% as it is made to contact with the cell suspension, which has a concentration of 10⁹CFU/mL, only with a dosage of 5g/L and for 3min. TTC-dehydrogenase determination and the measurement of extracellular DNA and RNA fully verified the sterilization mechanism of PVP-I₂/SiO₂.Insoluble macromolecular antibacterial material has more higher antibacterial activity relative to smaller molecular antibacterial owing to higher density of antibacterial groups on molecular chain. Furthermore, this insoluble antibacterial material protects the water from being polluted the second time due to macromolecular antibacterial immobilized on the insoluble carriers.